前端ajax用json方式请求 后端php 用 $GLOBALS['HTTP_RAW_POST_DATA'] 取值

　　　　　　　//参数--------------------------------------
            var params = {};
            params['module'] = "ai";
            params['action'] = "nextAiNode";
            params['apiVersion'] = "1.0";
            params['userId'] = "";
            params['sessionId'] = "";
            params['token'] = "";
            params['time'] = "";
            params['callerId'] = "13977666666";
            params['channelId'] = "1";

            params['para'] = {
                "event":"sessionStart",
                "asrText":"" 
            };
            //请求------------------------------
            $.ajax({
                type: "POST",
                url: "../webApi.php",
                contentType: "application/json;charset=utf-8",
                data: JSON.stringify(params), 
                dataType: "json",
                success:function (message) {
                    //alert("提交成功"+JSON.stringify(message));
                    $("#div_msg").html(JSON.stringify(message));         
                    
                },
                error:function (message) {
                    alert("提交失败"+JSON.stringify(message));
                }
            }); 

注意：   data: JSON.stringify(params),   中的 JSON.stringify() 方非常重要，如果没有则后端会取不到值。

php端

<?php
//获得post的json数据,
$postJson = json_decode($GLOBALS['HTTP_RAW_POST_DATA']);
//获得event参数
$eventName=$postJson->para->event;
$asrText=$postJson->para->asrText;    
 
$module=$postJson->module;
$action=$postJson->action;
$projectName=$postJson->projectName;    
$processName=$postJson->processName;    
$nodeName=$postJson->nodeName;    
$callerId=$postJson->callerId;  

?>